Chief Engineer Vandeberg
Lt. Commander Giotto
Enterprise is called in to help investigate the deaths of some men working
the deep Pergium mines on Janus VI. Kirk meets with the miners' leader,
Chief Engineer Vanderberg, who explains that three months previously they
had opened up some new levels in the mines that contained particularly
rich deposits. Since then, fifty men had been killed and their machinery
had started to corrode and disintegrate.
Nothing had been left of the men, except for some charring, and the deaths
had been occurring at increasingly higher levels, now nearing the miners'
living quarters. The Chief Processing Engineer claims to have seen the
creature responsible, which he describes as 'big and shaggy' and which
seemed to be immune to the type 1 phaser he had fired at it. Spock enquires
about a large silicon sphere in the office and is told that the miners
have found and destroyed thousands of the nodules in the new levels.
McCoy examines the remains of the latest victim, a man called Schmitter,
and finds that his body was corroded away by a powerful acid-like substance.
Spock maps the attack pattern and concludes that the creature must be
able to move incredibly fast, but a sensor scan shows no life signs in
the deserted mines. Another attack occurs and a critical part is stolen
from the colony's main reactor without which it will go critical in 48
hours. This convinces Spock that the creature must be intelligent and
he suggests that it may be silicon-based. He says that his would explain
why the ship's sensors failed to pick it up and that their type 2 phasers
should be set to compensate.
Security teams are brought in to search the tunnels and, after one of
their crewmembers is killed, Kirk and Spock track the creature through
a freshly cut tunnel. Only one creature can be detected although, due
to the large number of tunnels, Spock believes that there must once have
been many. The creature appears and they hit it with phaser fire before
it escapes down the tunnel. With the reactor due to fail imminently, the
Enterprise starts to evacuate non-essential mining personnel but Vanderberg
and some of the more vengeful miners remain behind.
Kirk and Spock separate when the tunnel branches and Kirk discovers a
cavern full of the silicon spheres which Spock, on being informed, advises
him not to damage. The creature appears before Kirk, causing a cave-in
that cuts them off. Kirk aims his phaser at it and notes that this persuades
the creature to back off. Spock calls on his communicator and urges Kirk
to kill it but he decides against it, preferring to wait for Spock to
make his way through to them.
In the meantime, the creature displays its phaser-induced injuries to
Kirk. On arrival, Spock attempts to mind-meld with the creature and discovers
that it is called a Horta. It is in such pain from its wounds that he
is forced to break contact, following which the creature uses its acid
to burn the words 'NO KILL I' into the rock floor. McCoy is summoned to
try and help it, complaining that he is a doctor, not a bricklayer. Spock
tries another mind-meld, this time physically touching the creature.
Now able to block out the pain, he discovers that the Horta is the last
of its kind and that the silicon spheres are its eggs, which it is protecting.
The Horta agrees to return the stolen reactor pump and leave the miners
alone as long as its remaining eggs are left untouched. McCoy manages
to patch up its wounds with thermo-concrete and everyone ends up happy.
By the time the Enterprise leaves orbit the baby Horta have begun to hatch,
digging tunnels everywhere and leading the miners to untold riches.